You can get in the situation when more POTS ports than 2 (like for this HGU type ONU) are needed. That could be a small office customer or building with more flats. It may also support a few TDM (time division multiplex) services such as DS1 or E1, via pseudowire emulation. This SBU from Fiberbit:
For example can have 16 FXS POTS ...
According our statistics, Single Family Unit's, or SFU's are most popular EPON ONU's ordered and shipped worldwide, and it really does not depends on a market or country. Of course, types of SFU's vary.
For example as one classifier, SFU's can be divided in Indoor Type ONU's, or in Outdoor type. If we look at various business models used by FTTx ...
